WASHINGTON (WUSA9) -- An estimated 10,000 motorcyclists circumnavigated the Outer Loop of the Capital Beltway in a commemoration of the September 11th attacks beginning at 11 a.m. Tuesday.

The ride left the Harley-Davidson of Washington D.C. dealership on Livingston Rd in Fort Washington and forced the closure of traffic on MD Rt. 210 for nearly an hour.

Around noon, traffic was piled up on one side of the Beltway because several bikers were involved in an accident. That accident happened between Rockville Pike and Connecticut Avenue. A fire truck blocked two left lanes and about 20 motorcycles were parked on left shoulder during investigation. There was a traffic backup to Georgia Avenue at one point.

We are also told that some bikers decided to go into D.C. and at least one biker hit a rickshaw. Three people were reportedly sent to the hospital.

The event "2 Million Bikers to DC" was organized on social media as a show of patriotism and commemoration. But many riders are also fueled by anger that organizers were denied a permit to parade in Washington, while the event originally dubbed the "Million Muslim March" was scheduled to go on near the Mall.

The "Million Muslim March" since renamed "Million Americans Against Fear," turned out a few hundred according to official estimates.

Organizers of the motorcycle event announced a last minute decision to circumnavigate the outer loop of the Capital Beltway about two hours before the start of the ride, as thousands began to gather in Ft. Washington. Organizers suggested after the Beltway event that riders break into smaller groups on their own and enter Washington if they wished. Organizers also implored riders not to confront or disturb the "Million Americans Against Fear" event.